It’s no secret that California and the U.S. government are singing very different tunes when it comes to climate change. The Golden State will gather a chorus of sorts at the Global Climate Action Summit, an international meeting of leaders and stakeholders in San Francisco Sept. 12-14.

Hosted by California Gov. Jerry Brown and others, the summit is designed to mobilize commitments by nonstate actors, such as companies, NGOs and local governments, to meet the world’s climate goals. Affiliated events hosted by Stanford institutes and programs will highlight climate impacts on children’s health and the significance of the 2009 U.S. Environmental Protection Agency Endangerment Finding decision, which stated that certain greenhouse gases “threaten public health and welfare” and has served as a major policy tool in regulating climate change.

Stanford Report spoke with some of the leaders of the affiliated events – professors Chris Field, Michele Barry and Marshall Burke – about climate change impacts to health and their hopes for the summit.

What connects climate and health, and what are the research gaps in understanding impacts?

Burke: Some of the biggest connections we’ve understood for a while: mortality rates rise when it’s really cold or really hot, rising temperatures tend to spread vector-borne disease to higher elevations and higher latitudes. But a host of new research is beginning to show us that the climate/health linkages probably run a lot deeper than we realized. We see mental health decline when it’s hot, violence increases, people sleep less and are less productive at work, and people’s cognitive function declines. So changes in climate likely affect our health in profound ways that we are only beginning to understand.

However, there are a number of important research gaps. We see in the data meaningful increases in both suicide and homicide rates when temperatures rise. But we don’t really have a good physiological or socioeconomic understanding of why this is happening. Understanding the mechanism behind these emerging climate-health linkages is going to be key to designing interventions that might help reduce negative impacts.

Barry: There are big questions on how climate affects health, especially for children, such as how wildfires cause asthma; how infectious diseases change with climate; and how air pollution and fossil fuels have impacted pregnant mothers and their children. The problem is that it takes many years to see the impact of climate on health. That’s why we need to continue surveillance, which this administration has actually diminished.

Field: We tend to think about direct effects of heat waves on mortality, but the effects go well beyond that. New studies point to rising risks from air pollution and from malnutrition related to crop failures. The changing risks of vector-borne illnesses like malaria are increasingly clear. But we still have limited understanding of risks from indirect effects. How will the increasing risk of wildfires influence exposure to air pollution? To what extent will water insecurity lead to additional violent conflict? These are important topics of ongoing research.

How has evidence for the EPA’s “Endangerment Finding” changed since it was made in 2009?

Field: For every area addressed in the 2009 Endangerment Finding, there is now much more evidence pointing unequivocally to risks to human health and welfare from emissions of heat-trapping gases. For some areas, change in evidence is mainly quantitative. In others, we not only have more evidence, but also see that risks have the potential to be more severe or pervasive. In 2009, we had solid evidence of risks to the major commodity crops, but we did not have solid studies on other important crops like fruits, vegetables and regionally important staples. New studies point to risks for a much wider range of crops and cropping areas. We now also understand risks in areas that were not discussed in the Endangerment Finding, such as those to national security which have played a rapidly increasing role in military planning.

The risk of endangerment is no longer focused only on the future. We now know that climate change is already altering the risk of heat waves, massive wildfires, heavy downpours and the most intense hurricanes.

What are some of the economic implications of the health concerns around climate change impacts?

Burke: A lot of the policy discussion around climate change involves a debate over the costs and benefits of mitigation. As we learn more about the negative health consequences of a warming climate, estimates of the benefits of mitigation tend to rise – often substantially. Put simply, we really value our health, and we are willing to pay a lot to not have loved ones (or strangers) get sick or pass away. If hotter temperatures cause more sickness and death, then mitigating future temperature rise brings bigger benefits, and this can change the cost-benefit calculation around how much we should invest in mitigation today.

What are your goals for the summit?

Field: Around the world, there are lots of bright spots, with nations, states, cities, companies, universities and individuals making real and meaningful progress. California is a beautiful example, with its strong leadership on climate action helping create thousands of jobs and sustain a vibrant economy. But progress is much too slow. My hope is that the summit will effectively illustrate the opportunities for climate action, stimulating a much wider range of actors to strengthen their commitments. We need to double or triple the rate of progress in tackling climate change. The summit can play an important role in getting us there.

Barry: My main goal for the summit is to communicate better to the public about how climate impacts the health of children. It’s really important that the science gets listened to. I think California needs to be a leader in this area. We need to be the role model in diminishing fossil fuel use. And I think that academics need to provide the science so that policy can change. It’s only when you get the hard facts, rather than false “facts,” that you can create smart policy.

Burke: People tend to have in mind certain impacts when they think about climate change. But all this new research suggests that the burden is likely to be much more shared than that, and that even wealthy societies are going to face substantial harm from rising temperatures, probably a lot more than we’re expecting. Communicating these potential costs and thus the benefits of investing in mitigation and adaptation is a key goal for me.

California’s wildfires have destroyed homes and communities, and even people hundreds of miles away are feeling the effects of smoke. Stanford faculty weigh in on the health effects and increasing frequency of fires.